Krill 'prefer sex in the dark'

When it comes to sex, krill like the lights off, and their maturation cycle can be altered with darkness, a new study has revealed.

When it comes to sex, krill like the lights off, and their maturation cycle can be altered with darkness, a new study has revealed.

An international team has carried out the study and found that the annual cycle of krill maturation as well as reproduction could well be altered by darkness immediately after spawning.

"We've been able to reset the animals' internal clocks so that they become sexually mature three months earlier than if they were exposed to a natural Antarctic light cycle," lead researcher So Kawaguchi of Australian Antarctic Division said.

In the study, three groups of krill were kept under different light, dark regimes. One group was exposed to four months of the natural Antarctic light cycle, followed by four months of darkness and four months of light.

A second group experienced four months of Antarctic light cycle followed by eight months of darkness. These two groups followed the same cycle of regression, maturation and reproduction as wild krill.

The third group of krill experienced one month of the natural Antarctic light cycle, followed by two months of darkness, and nine months of light. These krill reached sexual maturity three months earlier than the other groups - observed by changes in their (shell), which they shed as they grow.

"This study has shown that the transition from light to dark to light is important in controlling the timing of spawning under laboratory conditions," Dr Kawaguchi said.

The research promises to allow scientists to control when different groups of krill spawn, so that they have access to all phases of the life cycle (larvae, juveniles, sub-adults and adults) all year round.